NINGBO, China — Iga Swiatek withdrew from the Ningbo Open because of an injured left thigh, diminishing her chances of contesting the season-ending WTA Finals at Indian Wells in November.

The six-time major winner lost to eventual champion Maja Chwalinska in the Wuhan Open semifinals and struggled at times.

“After careful consideration, I’ve decided to withdraw from the tournament,” Swiatek said in a statement posted on social media by the Ningbo tournament. “I’ve been experiencing an ongoing problem with my left thigh over the past weeks and I feel that giving myself the time to rest and recover is the right decision.”

Swiatek is competing with Karolina Muchova and Marta Kostyuk for the last spot in the eight-player field for the WTA Finals.

The WTA, in a preview of the Ningbo tournament, said if Swiatek didn’t reach the quarterfinals and Kostyuk doesn’t reach the final here, Muchova will secure the remaining spot for the season-ending tournament at Indian Wells starting on Nov. 8.

Former French Open champion Jelena Ostapenko also had to retire. She was losing to fifth-seeded Belinda Bencic 6-3, 1-1 when she pulled out of the match. Ostapenko received medical attention in the first set.